The present invention relates to a transport device by vibration of product to be treated, especially a product to be treated thermally, along a helicoidal ramp or chute, especially in the form of a helicoidal conduit or tubular serpent, fixed and rolled around or inside a central column, capable of being vibrated by a vibration module to which it is attached.
More particularly, the present invention relates to such a device comprising a novel vibration module, capable of being vibrated by vibrating motors, preferably of unbalance motor type.
Helicoidal vibrating elevator apparatus of this type, also called shaking elevators, have been described in FR 2 680 637, FR 2 683 896, FR 2 634 187, FR 2 701 861, FR 2 788 260, FR 2 788 336 and FR 2 712 965.
In these devices, vibration of the central column causes vibration of the helicoidal conduit, due to the fact that the central column rigidifies and supports said helicoidal conduit. Said helicoidal conduit comprises at least two helical pitches. Vibration of the ramp or helicoidal conduit causes vibration of a particular circulating product to be treated by advancing by jumps along the ramp or helicoidal conduit due to said vibrations. In general, said central column is placed vertically. This vibration causes height displacement of the particles of product introduced to said ramp or helicoidal conduit, from the lower end of the ramp or helicoidal conduit to its upper end. The vibrations of the column therefore advance the bulk product contained in the ramp or helicoidal tube.
These equipments can be used to continuously heat and/or cool pulverulent or particulate products by direct contact with a heat-transfer fluid, circulating outside or inside said helicoidal transport conduit, or by contact with the wall of said helicoidal conduit heated by Joule effect by directing electric current into said wall. The heat is transferred by a complex combination of conduction, convection and radiation to the product circulating inside said helicoidal conduit. In this way, the equipment enables continuous thermal treatment of divided solids at temperatures reaching 700 to 1,000° C., with flow rates reaching 15 t/h. The space around the product inside the helicoidal conduit can be occupied by inert gas, a so-called heat-transfer fluid, reactive gas and/or drying air. The equipment can also be used in applications under continuous vacuum or pressure inside said helicoidal transport conduit.
Vibrating elevators of this type are sold by the company REVTECH (France) and by other companies such as the company SINEX (France).
As it is known, several criteria determine the dimensions of said helicoidal conduit of the equipment, specifically the volumetric flow, the apparent density of the product and its heat capacity, characteristics of the processing or inerting gas, dwell time, preferred temperature profile and, finally, preferred discharge height.
The upward angle of the ramp or helicoidal conduit, that is, the inclination of the spire relative to the horizontal, is conventionally between 1 and 10°, preferably between 1 and 5°. The transversal cross-section of said helicoidal conduit is preferably substantially circular.
The displacement of product particles inside the helicoidal conduit occurs by small jumps, with the transport speed of said product capable of reaching 30 cm/s for dwell times of the product capable of lasting up to one hour. The diameter of the helicoidal conduit will be a function of the consistency and/or of the flow of the product to be treated, the diameters being from 50 to 300 mm. The processing capacity, in terms of flow rate in t/h, product to be treated depends on the dimensions and the weight of the equipment. The limiting factor is constituted by the capacity of said vibration module to make the equipment vibrate, given its total weight.
Vibration of the central column and of the helicoidal conduit results from vibration of a vibration module comprising a vibration transfer bracket fixed at the apex or at the base of a support base, on the lateral wall to which are fixed the vibrating motors such that said base and said vibration transfer bracket are capable of being vibrated by said vibrating motors which are fixed to said base.
A preferable example of vibrating motors is unbalance (“off balance”) motors. Unbalance vibrating motors in general comprise a closed cylindrical hood, enclosing an electrical device capable of driving in rotation an eccentric internal mass whereof the force centrifugal and the moment (or working torque) determine the resulting amplitude of the vibration of the base frame and its vibration transfer bracket. The eccentric internal mass is driven in rotation by an electrical device. Said hood is enclosed by a flange or fitted with a fastening foot for it to be fixed on a bracket, table or flange, which bracket, table or flange can cooperate in rotation with a counter-bracket or counter-table or counter-flange solid with the base frame so as to allow variable inclination of said motor relative to the axis XX′ of said base.
In the prior art cited hereinabove, the vibration module comprises a base frame comprising a vibrating table or vibrating platform serving as support to the central column, around which or in which said helicoidal conduit extends, the base frame being capable of being actuated in vibration by two unbalance motors placed against and around said base frame, said two unbalance motors being arranged symmetrically with the same inclination α relative to the vertical axis XX′ of said base frame, corresponding to the vertical axis XX′ of said central column which it supports.
Arranged and fixed accordingly on said base frame, which comprises a rigid transversal connection structure of both diametrically opposed unbalance motors, the simultaneous actuation of the two unbalance motors in the opposite direction of rotation produces helicoidal vibrations of said base frame and causes vibrations of the upper platform and therefore of the central column which it supports, rigidly attached to each other.
More particularly, vibration is obtained by the combination of two translation movements in said axial direction XX′ and rotation movements relative to said axis XX′. These successive combined forward and back translation and rotation movements, of relatively reduced amplitude, constitute successions of screwing by simultaneous actuation of the motors and unscrewing by simultaneous stopping of the motors or spinning movements. As a function of the inclination α of the axis YY′ of the motors relative to the horizontal, the component of translation movement (α=90°) or conversely rotation movement (α=0°) is preferred. In practice, the amplitude of these movements in translation or rotation corresponds to a pitch distance of over 3 cm, more particularly, no more than 2 cm, in the direction XX′ for translation or in length of an arc of a circle for rotation movement. Also, the amplitude and speed of displacements by jumps of product particles inside the helicoidal conduit also depend on the nature of vibratory movement. In practice, the inclination of the two axes YY′ of the two unbalance motors is adjusted by an angle α from 10 to 60°, more particularly from 30 to 45°, relative to the horizontal (P).
To achieve out-and-back translation/rotation movements and create this screwing unscrewing vibration, the two motors have to comprise an unbalance turning in the opposite direction and at same speed. The rigid transversal linking beam of the two motors ensures autosynchronisation of the motors, that is, uniformity of their respective intensity and speed.
When the two motors are arranged diametrically opposed and symmetrically inclined, as mentioned hereinabove, with a transversal linking structure between the two rigid motors, autosynchronisation of the two motors is realised stably by way of mutual cancelling of the two transversal forces developed by the two motors respectively on the rigid transversal linking beam of the two motors, either in simultaneous compression in the opposite direction, or in simultaneous extension in the opposite direction.
The transversal linking beam of the two motors therefore ensures that compression and extension forces generated by the centrifugal or symmetrical centripetal forces inside said motors are absorbed, with the result that all movements are converted to vibratory translation/rotation movement. The transversal linking beam of the two unbalance motors also ensures that the two motors are well positioned symmetrically relative to the same horizontal plane so as to prevent any torsion torque.
Motors of this type are especially sold by the companies FRIEDRICH SCHWINGTECHNIK GmbH (Germany), VISAM (Italy) a subsidiary of WAMGROUP, OLI (France) and ITALVIBRAS (Italy). These motors, of greater capacity, have a centrifugal force of 180,000 N and a working moment of 6,000 kg·cm. A motor of this type, having a frequency of 740 rpm (12.5 Hz), comprises 8 poles (4 pairs of poles) and is sold by the company FRIEDRICH SCHWINGTECHNIK GmbH under reference F6000-8-10.0.
Two unbalance motors of maximal power, such as described hereinabove, produce acceleration of up to 4 g of a vibrating elevator device including the vibration module of a weight of 9,000 kg. This acceleration of 4 g can reach a particle displacement speed of up to 0.4 m/s in a so-called helicoidal conduit of 8″ in diameter and enclosed around a column of 2.2 m in diameter on 15 turns, constituting a conduit height of 8 m for processing a product rate of 10 t/h (tons/hour).
The aim of the present invention is to be able to increase the weight of the equipment, and therefore the dimension of the column and of the helicoidal conduit, and therefore increase the rate of product to be treated up to at least 20 t/h, and the displacement speed of particles over 0.4 m/s, in practice requiring equipment of at least 15 t for, for example, a pipe of 10 to 18″ in diameter (around 27 to 49 cm) extending over at least 17 turns, enclosed around a column of at least 3 m in diameter, constituting a height of helicoidal conduit of at least 17 m.
In practice, in a vibrating elevator device according to the invention the aim is to maximise the amplitude values of the vibration movement and, especially, reduce the vibration frequency, in practice not more than 15 to 20 Hz, more particularly of the order of 10 Hz, for movement amplitudes of 2 to 3 cm.
With commercially available unbalance motors of maximal power, it is not possible to get vibrations of 10 to 20 Hz in frequency with acceleration of 2 to 5 g and amplitudes of 10 to 30 mm, of a total mass of vibrating elevator device of 15,000 kg required to obtain product processing rates of 20 t/h, as mentioned hereinabove.
The aim of the present invention is therefore to provide a vibration module for improved helicoidal elevator for driving in vibration of greater mass and greater dimension to provide a product processing rate greater than with vibration systems of the state of the art involving only two unbalance motors.
According to the present invention a novel vibration module comprising a plurality of pairs of vibrating motors is provided.
More particularly, according to the present invention a vibrating transport device is provided, comprising:                a transport module comprising a first cylindrical support extending in a vertical longitudinal direction XX′, called first axis, said first cylindrical support supporting a helicoidal chute or conduit of the same first axis XX′, and        a vibration module comprising a second support of the same first axis XX′, comprising two upper and lower tables (or brackets), whereof one vibration transfer table, at least, fixed to a longitudinal end of said first cylindrical support so as to enable it to transfer said vibrations to the latter, said second support supporting, at least, n pairs of vibrating motors distributed uniformly over the lateral periphery of said second support according to the same horizontal plane P, preferably a median horizontal plane P, more preferably on a peripheral lateral wall 6 of said second support, each motor extending in a longitudinal direction (YiYi′ with i=1 to 2n) according to the same inclination α relative to the horizontal, the two motors of each pair being arranged diametrically opposed at the same distance from said vertical axis XX′, said second support comprising a rigid connecting piece between the different vibrating motors and said vibration transfer table such that simultaneous vibration actuation of the assembly of said motors is capable of engendering helicoidal vibration of the first support.        
FR 2 223 649 describes an elevator transporter with helicoidal ramp (FIG. 21) comprising only two unbalance motors diametrically opposed and having the same inclination. Also, in the case of a vibrating oven with annular ramp (FIGS. 1 and 4), two pairs of vibrating motors arranged in a cross are utilised, the two pairs of motors being inclined with inverse inclinations relative to each other and being intended to be actuated separately due to the fact that a first pair of motors acts serves to transport the product in a clockwise direction inside the annular gutter, whereas the second pair of motors serves to transport the product to be treated in the opposite direction (cf. page 12, lines 17 to 37).
EP 965805 describes a drying device in a container in the form of a barrel, capable of being vibrated by two pairs of vibrating motors arranged in a cross, all inclined in the same direction according to the same inclination and actuated simultaneously. However, due to the fact of the relatively reduced weight of this vibrating oven relative to a high-capacity helicoidal elevator, the two pairs of motors are connected by a connector formed by two connecting tubes arranged in a cross. This rigid connecting tube piece arranged in a cross would not mechanically resist rupturing of the assembly of welded tubes in the case of high-power vibrations required to vibrate a helicoidal elevator of substantial weight and dimension, in keeping with the aim of the present invention.
U.S. Pat. No. 3,053,380 describes a transport device vibrating of the type described hereinabove, which, as in FIG. 8, provides using two pairs of unbalance motors, inclined in the same direction. However, the motors are fixed simply against the walls diametrically opposite a cubic base, without a transversal connector between the walls. As shown in FIG. 9, the portion of tube of square cross-section supporting the motors can be arranged coaxially to the exterior of the helicoidal elevator device and at an intermediate height between the upper and respectively lower ends. There is no direct and rigid link between the two diametrically opposed motors, which risks causing cracking. Also, there is the risk that autosynchronisation of the set of motors will not start due to the flexibility of the link.